A review of more than 1,000 studies indicated that drinking "very hot" beverages is "probably carcinogenic to humans," the WHO's International Agency for Research on Cancer (IARC) announced on June 14.

"These results suggest that drinking very hot beverages is one probable cause of esophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible," IARC director Christopher Wild said.

The conclusion might be particularly unwelcome in Iran, where samovars are heirlooms and some aficionados believe the best cup of tea in the world is to be found.

But it's also where many people drink tea almost ritually at its hottest, frequently pouring the piping hot stuff into a saucer to cool it just enough to make it drinkable.

The practice contributed to a study by Iranian scientists published in 2009 in the British Medical Journal linking "very hot tea" to an increased risk of throat cancer.

The researchers had studied citizens in the Iranian northern province of Golestan, which has one of the world's highest rates of esophageal cancer and where large amounts of hot black tea are consumed regularly. Participants were asked about their tea-drinking habits, including how hot they drink it.

In Western countries, alcohol and tobacco are the main factors behind esophageal cancer. But in Golestan, where rates of smoking and alcohol consumption are low, the researchers concluded that "hot tea drinking" (70 degrees Celsius or more) appeared to be the strongest risk factor.

They identified three tiers of temperature for tea in the study and their corresponding risks, with a baseline of warm or lukewarm tea (65 degrees Celsius or less). Hot tea (65-69 degrees) "was associated with twice the risk" of throat cancer, and "drinking very hot tea (70 degrees or more) was associated with eight-fold increased risk."